Automated Teller Machines (ATM) are in general believed to be relatively secure devices since they handle consumer financial transactions and dispense currency. However, ATMs are susceptible to malware, viruses, and eavesdropping just like any other device having memory and processor capabilities.
One ATM resource that is particularly valuable to the ATM is the hard disk, which is relied upon during a boot process of the ATM to provide an authenticated version of the ATM's Operating System (OS).
Hard disks can be used for hiding malicious firmware, software, and/or a compromised OS. Yet, most ATM boots occur from the hard disk. A hard disk is an electromechanical physical device and components can and do fail over time; a hard disk may also lack storage capacity or lack acceptable access speed to support added functionality needed at the ATM.
As a result, hard disks do need replaced for ATMs, but replacing the hard disk poses substantial security risks.